1. Technical Field
The invention relates to an oscillator configured by mounting a resonator and a semiconductor device on a substrate. Further, the invention relates to an electronic apparatus, a moving object, and so on using such an oscillator.
2. Related Art
For example, in some cases, a quartz crystal oscillator is configured by mounting a quartz crystal resonator and a semiconductor device (IC) on a substrate. In such a quartz crystal oscillator, in some cases, the characteristic of the quartz crystal resonator is improved by overdriving the quartz crystal resonator, or the quartz crystal resonator is connected to an external measurement device to check the characteristic using two monitor terminals connected to the quartz crystal resonator prior to mounting the IC. Therefore, in general, the wiring pattern connecting the quartz crystal resonator and the monitor terminals is elongated, and becomes easy to be affected by an external noise such as a noise from a digital circuit. As a result, there is a problem that the oscillation frequency is shifted from a preset value, or a phase distortion is generated.
As a related-art technology, in JP-A-2012-186784 (paragraphs 0021-0022, FIG. 1) (Document 1), there is disclosed a quartz crystal oscillation device having a semiconductor package and a quartz crystal resonator mounted on a wiring board. The semiconductor package is provided with a first external terminal and a second external terminal used for connecting the quartz crystal resonator. On the wiring board, there are formed a first wiring pattern extending from the first external terminal and connected to one end of the quartz crystal resonator, and a second wiring pattern extending from the second external terminal in roughly the same direction as the first wiring pattern and connected to the other end of the quartz crystal resonator.
Further, on the wiring board, there is formed a third wiring pattern disposed in an area between the first wiring pattern and the second wiring pattern, and electrically connected to a ground power supply voltage. Thus, it becomes possible to reduce the pin-to-pin parasitic capacitance between the first external terminal and the second external terminal, and to reduce the pin-to-pin coupling noise. As a result, it is possible to satisfy the requirement of reduction of the parasitic capacitance and improvement of noise immunity.
However, in Document 1, the first wiring pattern and the second wiring pattern for connecting the quartz crystal resonator and the first and second external terminals extend in roughly the same direction to be elongated, and at the same time, the third wiring pattern connected electrically to the ground power supply voltage is formed between the first and second wiring patterns. Therefore, since the parasitic capacitance between the quartz crystal resonator and the ground wiring pattern increases, and the variable range of the oscillation frequency is narrowed due to the influence thereof, the characteristic of the oscillator is limited.
Further, Document 1 discloses the improvement of the noise immunity of the first external terminal and the second external terminal to be connected to the quartz crystal resonator, but does not particularly disclose the improvement of the noise immunity of other terminals.